Automatic reclosing circuit breaker



Oct. 13, 1953 J. M. WALLACE ET AL AUTOMATIC RECLOSING CIRCUIT BREAKER Filed NOV. 20, 1947 Insu/a/zbn Curran INVENTORS $07651 Mal/ace and -70hr) M .if/r/iny; .Jr:

WITNESSES:

Patented Oct. 13, 1953 UNITED STATES PATELNT OFFICE AUTOMATIC RECLOSING CIRCUIT BREAKER James M. Wallace, East McKeesport, and John W. Stirling, Jr., Pittsburgh, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 20, 1947, Serial No. 787,206

5 Claims. 1

This invention relates particularly to automatic reclosing circuit breakers of the type where closely successive circuit interrupting operations have different time characteristics.

Automatic reclosing circuit breakers are made to operate on closely successive operation as where a continuing fault occurs somewhere on the circuit, to open the circuit substantially instantaneously on the first one or two operations to prevent the blowing of fuses protecting various branches of the circuit so that if the fault clears service will be restored on the entire circuit, However, if the fault does not clear after such initial operation of the breaker, a time delay is interposed in the next circuit interrupting operation or operations of the breaker to give the fuse in the faulted branch of the circuit more time to blow. This requires coordination of the circuit opening time-current characteristics of fuses and the circuit breakers to obtain such selective action.

In the past, circuit breakers of this type have employed a solenoid for obtaining instantaneous separation of its contacts, and have used various time delay devices, such as fluid dashpots and mechanical tickers, to delay operation of the solenoid to obtain a delay in subsequent circuit interrupting operations. While such structures permit a degree of coordinationwith fuses, the range of currents over which this type of coordination was possible is extremely small, with coordination being particularly difiicult between breakers and fuses having the same current rating.

One object of this invention, therefore, is to provide a novel circuit breaker of the type described wherein coordination with other circuit I interrupting devices is possible over a wide range of current values.

Another object of this invention is to provide in a breaker of the type described having the first one or two circuit openings instantaneous in character, novel means causing subsequent closely succeeding circuit openings to be delayed with a time-current characteristic similar to that of a fuse of higher current rating.

Another object of this invention is to provide in a circuit breaker of the type described having the first one or two circuit opening operations instantaneous in character, novel means for decreasing the amount of force available to open the breaker and for imposing a time delay in the operation of the breaker opening mechanism on subsequent closely succeeding circuit opening operations.

Another object of this invention is to provide an automatic reclosing circuit breaker which is operative to substantially instantaneously open the circuit at a predetermined minimum overload current on the first one or two circuit opening operations in any sequence of closely successive circuit opening operations, and which is responsive only to a higher value of overload current to continue to open the circuit thereafter with an inverse time-current characteristic.

Another object of this invention is to provide a circuit breaker of the type described which normally has an instantaneous time characteristic on the first one or two circuit opening operations in any series of closely successive circuit opening operations, and means for counting the number of such successive operations, with novel means controlled by said counting means for delaying and decreasing the force available for opening the breaker for later circuit interrupting operations.

Another object of this invention is to provide in a circuit breaker having a series-connected solenoid coil which is responsive to overloads on the circuit to cause a circuit opening operation, novel means responsive to one predetermined circuit opening operation for decreasing the pull exerted by said solenoid on a closely succeeding circuit opening operation.

These and other objects of this invention will become apparent upon consideration of the following detailed description of preferred embodiments thereof, when taken in connection with the attached drawing, in which:

Figure 1 is a longitudinal section view through a circuit breaker embodying this invention;

Fig. 2 is a schematic showing of the circuit through the breaker shown in Fig. 1;

Fig. 3 is a view similar to Fig. 2 but showing a modified circuit arrangement;

Fig. 4 is likewise a schematic circuit diagram illustrating still another form of the invention;

Fig. 5 illustrates still another circuit which may be employed in a circuit breaker of the type shown in Fig. 1; and

Fig. 6 is a chart showing typical time-current curves for a fuse and circuit breakers.

The circuit breaker illustrated in Fig. 1 is contained in a metal tank 2 having an open top adapted to be covered by a hollow cover structure 4 which may be secured to tank 2 in any desired manner. Preferably, the major part of the interior of tank 2 is covered by a suitable insulating liner 3, of any desired insulating material, such as fiber or the like. The circuit breaker operating mechanism is all adapted to be mounted in cover 4, which may have supports 6 (only one of which is shown) at least partly of insulating material for supporting a supporting casting 8 and a supporting plate It between which a solenoid coil l2 may be mounted. Stationary contacts H3 for the breaker may in turn be suspended from supporting plate ill by arc chutes 16 of insulating material, such as fiber or the like.

A bridging contact bar 18 is adapted to bridge stationary contacts i4, and is mounted on the lower end of a contact rod 22, as by a pivot 25, about which the bridging contact may have limited pivotal movement. The upper end of contact rod 22 is connected by a pair of pivoted connecting links 24 of insulating material, such as fiber or the like, to the common pivot 26 of a pair of toggle levers 28 and 30. Toggle lever 28 is adapted to be held in engagement with a pivot bracket 32 supported from cover 4 by a coil tension spring 34 secured at one end to cover 4, and at the other end engaging an opening in tog le lever 36.

Spring 34 acts, at the position of the parts shown in Fig. l, to bias bridging contact [8 into engagement with stationary contacts 14 of the breaker with a predetermined pressure. However, if contact rod 22 is moved upwardly, the pivot point 26 of toggle levers 28 and 30 moves upwardly with the contact rod and this movement is opposed by contact pressure spring 34. However, the line of action of contact pressure spring 3 3 approaches the on-center position of toggle levers 28 and 30 during the first part of contact opening movement, so that the opposition of this spring to such opening movement rapidly decreases to substantially zero when the toggle levers are at their on-center position. The contact separating movement required to move toggle levers 28 and 36 from their positions shown in Fig. 1 to their on-center position is kept small because separation of these levers is limited by a hook portion 29 on toggle lever at which extends through an opening in toggle lever 28 to limit separation of the levers to a relatively small amount. Furthermore, during the first part of contact separating movement, the levers 28 and 36 are moved to their on-center position as described above, and at this position, lever 36 engages lever 26 so that further relative movement in the same direction is prevented, and accordingly, contact pressure spring 3d offers substantially no opposition to further contact separation.

After a circuit opening operation by contact rod 22, the force 9f gravity acts on bridging contact 2t and contact rod 22 to cause these parts to move downwardly toward stationary contacts i4. As is the case during the latter part of contact separating movement, contact pressure spring 34 will have substantially no efiect on the circuit closing operation, until the line of action of contact pressure spring 3% moves below the pivot point of toggle lever 28 on bracket 32, whereupon this spring becomes effective suddenly to rapidly move the bridging contact into engagement with stationary contact 52 and to exert the aforementioned contact pressure thereon.

In order to manually operate the circuit breaker contacts, and also to provide for a locked open condition of the breaker, there is provided a pair of toggle levers 36 and 36 connected by a knee pivot pin at, with lever 36 being pivotally mounted in cover 4 as by a pivot pin 42, and being extended beyond this pivot pin to the exterior of cover where it normally is positioned beneath a hood portion 46 integral with the cover. The

handle extension 44 of lever 36 has an operating eye 48 at the outer end thereof for receiving a hook stick or similar operating member. The other toggle lever 38 is provided with a slot 56 at its outer end for receiving a pin 52 mounted between spaced supporting lugs 5| integral with cover 4. A coil compression lock-out spring 56 is mounted on toggle lever 38 so as to react between supporting lugs 54 and a shoulder provided at the inner end of toggle lever 38. Preferably, toggle lever 38 has an inwardly and downwardly extending operating extension 56 adapted to be engaged by automatic counting means, as will be described.

It will be observed that toggle levers 36 and 36 are shown in Fig. 1 of the drawing as being held at a position slightly below center by spring 56, with knee pivot 40 below a line drawn between pivot 42 of lever 36 and supporting pin 52 for lever 38, and that .a :stop bolt 68 mountedin hood 46 of the cover defines this over-center position of the toggle levers. When it is desired to manually open the breaker contacts, handle 14 may be pulled downwardly to move the .knee pivot 40 of toggle levers 36 and 3B upwardly over center whereupon spring 56 assists in further upward movement of toggle knee pivot '46. Inasmuch as the toggle knee pivot pin 40 is extended to lie beneath a flange on toggle lever 28, upward movement of this pivot pin likewise causes upward movement of toggle lever 28, contact rod 22, and bridging contact 6 to an open circuit position. Following such a manual circuit opening operation, handle 44 may be manually moved upwardly back to the position shown in Fig. l where toggle levers '36 and 38 will be maintained by spring 55, to thereby permit re'closing of the breaker contacts in the same manner described above. With toggle levers 36 and 38 in the positions thereof shown in Fig. 1, it is obvious that operating extension '58 of lever 38, if moved upwardly, will have the same effect as downward'movement of handle 14, that is, to cause opening of the breaker contacts, to a locked-open position at which they are held by spring 56.

For the purpose of automatically separating bridging contact l8 from stationary contacts 14 of the breaker in response to overloads, there is provided an actuating sleeve 60 which receives an intermediate portion of contact rod 22, with the lower end of this sleeve being threaded into a solenoid core 62 having a central opening for receiving contact rod 22, and being slidably mounted .in a central opening provided in coil supporting plate III. A light coil compression spring 64 reacts between a pin 66 on contact rod 22 and solenoid core '62 to normally bias the latter "to the position shown in Fig. l. Preferably, solenoid coil [2 is provided with suitable insulation 63 covering the coil, and the interior of the coil additionally has a cylindrical dashpot sleeve 10 of insulating material, such as fiber or a molded insulating material received therein. For the purpose of limiting upward movement of actuating sleeve 60 on contact rod 22, the latter is provided with a flange 12 adjacent the upper end thereof. The upper end of dashpot sleeve 10 is provided with an annular outlet passage 14 formed in supporting casting 8, and communicating with a laterally extending vent passage 16 also formed in the supporting casting which opens to the interior of casing 2.

It will now be apparent that upon the passage of currents through solenoid coil ll of a value sufiiciently high to attract core 62, that the latter will be moved upwardly while stressing spring 64. Depending upon whether or not vent passage 16 is open or closed by means to be hereinafter described, upward movement of core 62 and actuating sleeve 60 will be relatively fast (if vent passage 16 is open) or relatively slow (if vent passage 76 is closed), due to the necessity of liquid trapped within the dashpot sleeve 16 escaping through the relatively small clearancesbetween core 62 and the opening in supporting plate II) when the vent passage is closed. In either case, however, spring 64 eventually becomes compressed to an extent that contact pressure spring 34 is overcome and contact rod 22 then begins to move upwardly to separate bridging contact la'from stationary contacts l4 in the manner previously described. In the event of any difficulty with spring 64, upward movement of core 62 and actuating sleeve 69 will eventually cause the latter to engage the flange 12 on contact rod 22 to positively separate bridging contact [8 from stationary contacts I 4. When solenoid coil I2 becomes deenergized, the contacts may close in the manner previously described, except that the speed of reclosing movement will be dependent, as is the speed of contact opening movement, upon whether or not vent passage 16 is open or closed.

For the purpose of counting closely succeeding circuit interrupting operations of the circuit breaker, there is provided a cylindrical sleeve 18 mounted in an opening provided in supporting casting 8 intersecting vent passage 16, and a counting piston 80 is adapted to be mounted in sleeve 18. The lower end of sleeve 78 is closed by a plug having a small opening controlled by a ball check valve 82 so that while fluid may be freely drawn into the lower end of sleeve 18, it cannot escape outwardly from the lower end of the sleeve. Counting piston 8!! has a reduced upwardly extending rod portion provided with a plurality of spaced flanges 84 thereon, and above this it has secured thereto one above the other, a plurality of extensions 86, 88 and 90, for a purpose to be described.

A pawl lever 92 is pivoted at one end as at 94 on supporting casting 8 and has its other end engaging the top of a collar 96 secured to actuating sleeve to so that the lever will be moved upwardly each time the breaker contacts separate. Pawl lever 92 has a pawl member 98 mounted thereon which is adapted to engage beneath a flange 84 of the counting piston to move the piston upwardly each time the breaker contacts separate.

It is believed clear that upon the occurrence of a circuit opening operation, counting piston 80 will be moved upwardly a predetermined distance by pawl member 98 and when the breaker contacts are reclosed, counting piston 80 will remain at the position it was advanced on the preceding circuit opening operation. Counting piston 86 will return very slowly to its normal lowermost position illustrated in Fig. 1 under the force of gravity, it being retarded in such return movement by the necessity of displacing liquid drawn into the lower end of sleeve 18 when the piston was advanced, between the relatively small clearance between the piston and sleeve 18. However, if a number of circuit opening operations occur in close succession, counting piston 89 will not have time to return to its normal lowermost position shown in Fig. 1, because when the contacts reclose, they will immediately reopen, and this time pawl member 98 will engage the next lowermost flange 84 of the counting piston to advance the latter a further amount upwardly, and this will continue until the uppermost extension 90 of the counting piston engages operating extension 58 of toggle lever 33 to move the knee pivot 40 of toggle levers 36 and 38 upwardly over center, whereupon the breaker contacts will be locked out in the manner previously described.

Another function of counting piston is to control vent passage 16 leading from the upper end of dashpot sleeve 10. Normally the small cross section area extension of counting piston 80 is positioned in the region of the transverse openings through cylindrical sleeve 18 in alignment with vent passage 16, so that relatively free venting of fluid from the upper end of dashpot sleeve 10 is possible, and accordingly, upward movement of solenoid core 62 is relatively unimpeded so that the first circuit opening operation will occur substantially instantaneously after the current through coil !2 reaches a value sufficient to attract core 62. Assuming that the contacts then reclose and are again immediately reopened due to excess current still being present in the circuit, counting piston 80 itself may be advanced to a position blocking vent passage 16, or this may not occur until the third close-1y succeeding circuit interrupting operation, depending upon the length of sleeve 18 in which the piston is located and on the length of the piston and its reduced upward extension. In either case, piston 80 will eventually be advanced to a position where it does block vent passage 16 so that the next closely succeeding circuit interrupting operation will be delayed due to the dashpot action of core 62 in dashpot sleeve 10 located within solenoid coil [2.

Of course, if the excess current condition through solenoid coil [2 causing a circuit opening operation of the breaker does not persist, counting piston 80 will slowly reset as previously described, so that if a permanent condition comes on the circuit at a later time, the breaker will again go through the same sequence of one or two fast circuit opening operations followed by time delay operations to lock-out the breaker after the predetermined number of closely successive operations has occurred to cause extension of the counting piston to engage and move operating extension 58 of toggle lever 38 upwardly.

The structure thus far described, except for the making of the upward extension of counting piston 80 in three parts (86, 88 and 90) is substantially identical with the breaker constuction disclosed and claimed in Patent No. 2,626,329 which issued on January 20, 1953 to J. M. Wallace et a1., entitled Circuit Interrupters, and assigned to the same assignee of this invention. Accord ingly, for a more complete description of the structure and operation of the breaker parts thus far described, reference is hereby made to the aforesaid patent of Wallace, et a1.

Referring to Fig. 6 of the drawing, a breaker such as that described up to this point will have time-current characteristics on the first one or two instantaneous circuit interrupting operations generally like the curve I, and when vent passage 16 is closed, the curve will then shift to the right at its lower end as shown by the curve T in Fig. 5. In coordinating such circuit breakers with fuses as was mentioned at the outset, the difficulties are readily apparent when the shape of the time-current curve of a fuse F is considered in its relation to the circuit breaker curves '1 and I. It will be observed that for this given current rating, the fuse curve has a distinct inverse time-current characteristic substantially throughout its current range. For the .same cur- .rent rating, the instantaneous time-current characteristic of a circuit breaker has relatively little inverse time-current character, and lies entirely to the left of fuse curve F so that the breaker is clearly capable when operating instantaneously to protect a fuse of the same or lower current rating because it will always open before the .fuse can interrupt the circuit. However, while the introduction of time delay means .for delaying movement of the quick-acting operating means, such as a solenoid, does result in a shifting of the lower end of the instantaneous timecurrent curve to the right as shown at T to allow more time for fuses to blow, accurate coordination of such a breaker and fuses is clearly impossible at least where the breaker and fuse have substantially the same rating because throughout most of the current range the breaker will open before the fuse, and will only open later at the very highest overloads. Moreover, complete coordination is not possible in any case because of the difference in slope of curves F and'T.

According to this invention, it is proposed to cause the breaker to have one or two first instantaneous circuit opening operations on continuing overloads having a characteristic like that shown at I in Fig. 6, but thereafter to have a time-current characteristic which will lie entirely to the right of fuse characteristic F so that a clear selective action over a wide current range is possible for coordination purposes. Thus, if the breaker has a time-current characteristic such as R after the first one or two instantaneous circuit opening operations, it will be plain that the fuse will have a clear opportunity to blow and isolate the fault before the breaker opens. Moreover, the breaker still furnishes backup protection because it will always open eventually in case of any difficulty in the operation of the fuses with which it is coordinated. .In other words, it is necessary that the later openings of the breaker have an inverse time-current characteristic similar to that of a fuse because without the employment of such a time delay means,

the later openings of the breaker, if vinstantaneous, would have a time-current characteristic such as that indicated at IR in Fig. 6, which would be positioned so far to the right in order to permit selective operation of the fuse that there would be a current range up to current A wherein the breaker would never operate after its first instantaneous operations on any given continuing overload.

In order to achieve later circuit opening operations of the breaker with a time-current characteristic like that illustrated at R in Fig. 6, it will be observed that the upper extensions 86, 88 and 99 of counting piston 80 form switching means operated in accordance with the position of counting piston 86. Thus, there is provided at one side of the upper extensions of counting piston 80, stationary contacts H10 and IE2 mounted on a supporting plate 104 of insulating material, supported from supporting casting 8. At the opposite side of the upper extensions of counting piston 89, a stationary contact 186 is located at a point intermediate opposed contacts 105 and 102 with contact I05 being supported from supporting casting '8.

The circuit through the breaker may now be traced from one breaker terminal mounted on :a bushing 1-08 on hollow cover 4, by way or conductor Hi] to a stationary contact [-4 of the breaker. .At the closed circuit position of the breaker, the circuit therethrough continues by way of bridging contact [8 to the other stationary contact [4, and by a conductor I I2 to stationary contact 1-06 of the counting piston. Stationary contact 102 is connected by a conductor ill to an intermediate turn of solenoid coil 12., with one "end of the solenoid coil connected to stationary contact Hill by a conductor '1 l6, and the other end of the coil being connected by a conductor H8 to another terminal bushing (not shown) which may also be mounted on cover 4.

It will be observed that the upper extensions 86, 88 and 90 of the counting piston are of different materials, with the extensions 86 and being of an insulating material, and with extension 88 being of an electrical conducting material. Accordingly, at the normal position of counting piston 80, stationary contacts I00 and l'flfi are bridged .by counting piston extension 88 so that (Fig. 2) the entire current flowing in the circuit goes through the entire solenoid coil 12. This gives the maximum possible number of ampere turns for instantaneously opening the breaker contacts. However, as integrator piston 80 is advanced upwardly on the .first or second circuit interrupting operation in any sequence of closely succeeding circuit interrupting operations, the circuit to the lower part of solenoid coil 12 is opened because counting piston extension 88 moves up beyond stationary contact I00 into engagement with stationary contact "2 to establish a circuit :from this contact to contact [06 so that, as illustrated, the circuit current flows through only part, which may be about one-half, of solenoid coil [2. This results in a substantial reduction in the number of ampere turns and a corresponding reduction in the force available to attract solenoid core '62 at the same value of overload current. This results in the time-current curve R shown in Fig. 6, being shifted to the right to .give :a relatively wide range of selectivity between the first instantaneous operation of the breaker and later delayed operations for coordination with fuses. While the reduction in the number of ampere turns of solenoid coil I2 in later operations in any sequence of a plurality of closely successive circuit interrupting operations results in an increased current rating for such operations, the important factor in achieving a time-current characteristic such as B. '(Fig. 6) is that for the same value of overload current, the force acting on solenoid core 62 is reduced; or stated in another way, the current at which core '62 will be picked up by solenoid coil 12 is raised. The operation of reducing the number of ampere turns of solenoid coil 12 should be coordinated so as to occur at the same time as the closing of vent passage 18 so that a curve such as R is achieved, which not only is shifted in its entirety to higher currents throughout its range, but retains an inverse time-current characteristic approaching that of the fuses with which it is coordinated. This requires the introduction of a time delay means which may be of the dashpot type illustrated, at the same time the reduced operating force is made effective.

The particular arrangement shown in Fig. 3 involves the use of an auxiliary coil I20 which should be mounted in magnetically coupled relation with respect to solenoid coil 12 with one end or this coil connected to one stationary contact I22, and the other end of the auxiliary coil connected through a variable resistor I28 to a stationary contact I24 by means of a conductor I30.

It is believed apparent that when counting piston extension 88 bridges stationary contacts I22 and I24, that the circuit of auxiliary coil I20 will be closed to divert some of the flux of solenoid coil I2, dependent upon the adjustment of resistor I28, because of the magnetic coupling of the two coils, to thereby reduce the force exerted by solenoid coil I2 to attract its core 62. An advantage of auxiliary coil I20, of course, is that the same coil and resistor may be used on existing circuit breakers regardless of the size or rating of solenoid coil I2 which may be employed. The obvious advantage of variable resistance I28 is to vary the current at which solenoid coil I2 can pick up its solenoid core 62 to thus vary the distance between the breaker time-current characteristic curves I and R, all for the purpose of obtaining a greater or less degree of selectivity to properly coordinate with the particular ratings of fuses which may be encountered in service.

The arrangement shown in Fig. 4 is similar except that here a resistor I32 is connected between one end of solenoid coil I2 and stationary contact I22, with the opposite stationary contact I24 being connected by a conductor I34 to the opposite end of solenoid coil I2. It is apparent that in this arrangement that resistor I32 will be connected in shunt with the entire solenoid coil I2 when counting piston extension 88 arrives at the position shown in Fig. 4 where it bridges the stationary contacts I22 and I24, to thus reduce the current through the coil, and result in shifting the time-current characteristic as before.

A similar shunting resistor arrangement is illustrated in Fig. 5, except that instead of a switch operated by counting piston 80, resistor I42 is adapted to be connected in shunt relation with solenoid coil I2 by a bimetal switch member I38 adapted to be heated by a heating resistance I 36 permanently connected in series circuit between solenoid coil I2 and one stationary contact I4 of the breaker. Bimetal member I38 is supported at one end in any desired manner and is constructed in a manner well known in the art of a pair of metallic laminations having different coefiicients of thermal expansions, respectively, such as a lamination of steel and a lamination of brass or copper. The laminations are secured together in any desired manner, as by welding or the like, with the lamination having the higher coefiicient of thermal expansion being positioned lowermost so that when bimetal element I38 is heated, it will deflect upwardly to engage a contact I ll! and thus establish the shunt circuit for solenoid coil I2 including resistor I42. Inasmuch as heating resistance I36 is in series circuit with solenoid coil I2, it will be heated by the fault current of the first and second circuit interrupting operations so that if these operations occur relatively close together, sufiicient heat will thus be developed to cause bimetal element I33 to deflect and engage shunt contact I40.

It is believed apparent that in each of the embodiments of the invention described above, an automatic reciosing circuit breaker is provided having means for effecting a first one or two instantaneous circuit opening operations, after which a time delay is imposed on the instantaneous acting contact operating means, and the force operating such actuating means is simultaneously decreased so that in all cases the timecurrent characteristic of these two different operations of the breaker will generally correspond to the characteristics I and R shown in Fig. 6. This results in all cases in providing a relatively wide current range represented by the range of currents separating curves I and R, over which selective operation to obtain proper coordination with fuses and other circuit interrupting devices is possible throughout the current range of such devices and the circuit breakers. In at least one embodiment of the invention, this current range in which coordination is possible may be varied by a simple variable resistance (shown in Fig. 3), and several different arrangements are disclosed for obtaining such relatively wide current range in the different operations of the breaker for purposes of coordination.

Having described preferred embodiments of the invention in accordance with the patent statutes, it is desired that the invention be not limited to these particular structures inasmuch as it will be apparent to persons skilled in the art that many changes and modifications may be made in these structures without departing from the broad spirit and scope of this invention.

We claim as our invention:

1. An automatic reclosing circuit breaker, comprising, separable contacts, current responsive means having a part which is moved in response to overloads on the circuit a predetermi ed amount before causing a quick separation of contacts, means for automatically closing said contacts following a circuit opening operation, means actuated during a cycle of operation. of said breaker comprising a circuit opening and succeeding closing operation for counting the number of closely successive cycles of operation, means for slowly resetting said counting means so that it will not count widely spaced cycles of operation, normally ineiiective time delay means operativcly connected with said part, a ccnnec tion between said time delay means and said counting means for rendering said time delay means eiTective to delay separation of said contacts only in response to a predetermined cycle of operation of said breaker in a series of closely successive cycles of operation, and means also connected to said counting means and said current responsive means for causing the latter to respond only to substantially higher values of current on the aforesaid predetermined cycle of operation, to the -eby obtain a relatively wide cur rent range of operation for purposes of coordination with other circuit interrupting devices.

2. An automatic reclosing circuit breaker COll1-- prising, separable contacts, a solenoid coil responsive to overload currents to attract and move a core at least a predetermined distance, means actuated by said core after traveling said pre determined distance for causing separation of said contacts, means for automatically closing said contacts following a circuit opening opera tion, means actuated during a cycle of operation of said breaker comprising a circuit open ing and succeeding closing operation for coun ing the number of closely successive cycles of operation, means for slowly resetting said count ing means so that it will not count widely spaced cycles of operation, normally ineiiective time delay means operatively connected with said part, a connection. between said time delay means and said counting means for rendering said time dela-ymeans efiective to delay separation of said contacts only in response to a predetermined cycle of operation of said breaker in a series of closely successive cycles of operation, switch means electrically connected in a shunt circuit with at least a part of said coil, means actuated by said counting means for operating said switch means in response to the cycle of operation including said predetermined circuit opening operation for closing said shunt circuit, and means iforadjusting the impedance of said shunt circuit.

3. An automatic reclosing circuit breaker comprising, separable contacts, a solenoid coil responsive to overload currents to attract and move a core at least a predetermined distance,

means actuated by said core after traveling said predetermined distance for causing separation of said contacts, an auxiliary coil magnetically coupled with said solenoid coil, means for automatically closing said contacts following a circuit opening operation, means actuated during a cycle of operation of said breaker comprising a circuit opening and succeeding closing operation for counting the number of closely successive cycles of operation, means for slowly resetting said counting means so that it will not count widely spaced cycles of operation, normally ineiiective time delay means operatively connected withsaid part, a connection between said time delay means and said counting means for rendering said time delay means eiiective to delay separation of said contacts only in response to a precis termined cycle of operation of said breaker in a series of closely successive cycles of operation, switch means electrically connected in circuit with said auxiliary coil, and means actuated by said counting means for operating said switch means in response to the cycle of operation including said predetermined circuit opening operation to close said auxiliary coil circuit.

4. An automatic reclosing circuit breaker comprising, separable contacts, a solenoid coil responsive to overload currents to attract and move a core at least a predetermined distance, means actuated by said core after traveling said predetermined distance for causing separation of said contacts, an auxiliary coil magnetically coupled with said solenoid coil, means for automatically closing said contacts following a circuit opening operation, means actuated during a cycle of operation of said breaker comprising a circuit opening and succeeding closing operation for counting the number of closely successive cycles of operation, means for slowly resetting said counting means so that it will not count widely spaced cycles of operation, normally inefiective time delay means operatively connected with said part, a connection between said time delay means and said counting means for rendering said time delay means effective to delay separation of said contacts only in response to a predetermined cycle of operation of said breaker in a series of closely successive cycles of operation, switch means electrically connectedin circuit with said auxiliary coil, means actuated by said counting means for operating said, switch means in response to the cycle of operation including said predetermined circuit opening operation to close said auxiliary coil circuit, and means for adjusting the impedance of said auxiliary coil circuit.

5'. An automatic reclosing circuit breaker comprising, separable contacts, a solenoid coil responsive to overload currents to attract and move a core at least a predetermined distance, means actuated by said core after traveling said predetermined distance for causing separation of said contacts, means for automatically closing said contacts following a circuit opening operation, means actuated during a cycle of operation or said breaker comprising a circuit opening andv succeeding closing operation for counting the number of closely successive cycles of operation,

'. means for slowly resetting said counting means so that it will not count widely spaced cycles or operation, normally ineffective time delay means operatively connected with said part, a connection between said time delay means. and said counting means for rendering said time delay means effective to delay separation of said contacts only in response to. a predetermined cycle of. operation of said breaker in a series of closely successive. cycles of operation, switch means electrically connected in a shunt circuit with at least; a part of said coil, and means actuated by said counting means for operating said switch means in response to the. cycle or operation including said predetermined circuit opening operation for closing said shunt circuit, to. thereby obtain a relatively wide current range of operation for purposes of coordination with other circuit interrupting devices.

JAMES M. WALLACE. JOHN W. STIRLING, JR.

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